A 0.25 M solution of potassium dichromate (K2Cr2O7) is used to oxidize 50.0 mL of a solution containing 0.15 moles of ferrous ions (Fe²⁺) to ferric ions (Fe³⁺). Calculate the volume of the K2Cr2O7 solution required for the complete reaction.
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The balanced equation for the reaction between potassium dichromate (K2Cr2O7) and ferrous ions (Fe²⁺) is:
6Fe²⁺ + Cr2O7²⁻ + 14H⁺ → 6Fe³⁺ + 2Cr³⁺ + 7H2O
From the equation, we can see that 6 moles of Fe²⁺ react with 1 mole of K2Cr2O7.
Given that there are 0.15 moles of Fe²⁺, we can calculate the moles of K2Cr2O7 required:
moles of K2Cr2O7 = (0.15 mol Fe²⁺) / (6 mol Fe²⁺ / 1 mol K2Cr2O7) = 0.025 mol K2Cr2O7
Next, we can use the molarity of the K2Cr2O7 solution to calculate the volume required:
moles of K2Cr2O7 = Molarity × Volume
0.025 mol K2Cr2O7 = (0.25 mol/L) × Volume
Volume = 0.025 mol K2Cr2O7 / 0.25 mol/L = 0.1 L = 100 mL
Therefore, 100 mL of the 0.25 M solution of potassium dichromate (K2Cr2O7) is required for the complete reaction.
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